JPS6029523B2 - Novel polymer flocculant and flocculation treatment method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel acrylamide-based polymer flocculant from which acrylamide monomers are substantially removed, and a flocculation treatment method using the same.

Acrylamide or a monomer mixture of acrylamide and a vinyl compound capable of being polymerized easily polymerizes to produce a water-soluble acrylamide-based polymer.

These polymers have a flocculating effect superior to many other water-soluble vinyl compound polymers, and are widely used as flocculants in sedimentation of ores, treatment of various industrial wastewaters, and dewatering of sewage sludge. Acrylamide-based polymers used as flocculants are usually produced at a monomer concentration of 5 to 5 by aqueous solution polymerization.
It is produced by carrying out a polymerization reaction at a concentration of 3% by weight, drying and pulverizing the obtained polymer.

As for flocculants, polymer viscous steel liquid after the completion of polymerization reaction is also currently used as a product. It is preferable that this type of polymer for a flocculant has a large molecular weight, and in particular, in the case of nonionic and anionic flocculants, a polymer having a molecular weight of 10 million or more is required.
The amount of catalyst used in the polymerization is therefore generally proportional.
Furthermore, since the polymerization reaction is carried out at the above-mentioned monomer concentration, especially in the production of high molecular weight polymers, the polymer becomes gelatinous in the late stage of the reaction, making it difficult for the reaction to proceed. For these reasons, it is generally difficult to obtain a polymerization rate close to 100%, and ordinary acrylamide-based polymers contain unreacted acrylamide monomers and 0.1% to several weight% remaining. are doing. Since acrylamide monomer is highly toxic, products containing unreacted acrylamide monomer pose a pollution prevention problem, and their use is restricted.

For example, it is stipulated that the amount of acrylamide monomer contained in polymer flocculants used in water treatment plants, food wastewater purification, etc. should be 0.05% by weight or less. There are many countries. For this reason, various methods have been proposed for reducing or removing unreacted acrylamide monomer. For example, the most reliable and simplest method is known to be washing and extraction using a solvent that does not dissolve the polymer but dissolves only the acrylamide monomer, such as methanol. However, this method requires a large amount of solvent, and its recovery and
The disadvantage is that the product price is high due to processing of pot residue, complicated operation, drying process, etc. There is also a known method of converting unreacted acrylamide monomers into other harmless substances by adding substances that selectively react with acrylamide monomers, such as ammonia and amines. No. 50-40689).

However, this method is limited to cases where acrylamide-based polymers with fluidity are to be produced at a low monomer feed concentration, that is, cases where productivity is extremely poor. This is because, at a high monomer concentration of 1% by weight or more, it becomes impossible to uniformly mix ammonia, amine, etc. into the gel-like polymer produced, and they completely react with unreacted acrylamide monomer. This is because it cannot be done. Furthermore, even if these substances are added when the polymer is dissolved, they are not preferred for cationic polymers. Furthermore, recently, in addition to the redox polymerization initiator conventionally used as a catalyst system, a method of reducing the acrylamide monomer by using an azo polymerization initiator (Japanese Patent Publication No. 47-2643 Bikarasu) has been developed. Official bulletin, Hakama Sekisho 50-14428 number and Tokusekki Sho 50-1966
No. 8y (see each specification) has been developed.

Although this method is a considerable improvement, it often results in a reduction in molecular weight and is unsatisfactory in terms of a reduction in acrylamide monomer. The present inventors have conducted various studies to develop an advantageous flocculant treatment agent that eliminates the drawbacks of these conventional methods. It has been found that the reacted acrylamide monomer can be substantially completely removed.

The present invention is based on this knowledge, and uses as active ingredients an acrylamide homopolymer and/or a copolymer mainly composed of acrylamide, and a bacterium belonging to the genus Nocardia or an enzyme thereof having the ability to decompose acrylamide monomer. An acrylamide-based polymer flocculant capable of substantially removing unreacted acrylamide monomer in the polymer, characterized by:

Furthermore, the present invention provides an acrylamide homopolymer and/or a copolymer mainly composed of acrylamide, and an acrylamide-based polymer aggregate having an ability to decompose acrylamide monomer/having bacteria belonging to the genus Cardia or an enzyme thereof as an active ingredient. An acrylamide-based polymer flocculant is used in the flocculation treatment in a form dissolved in an aqueous solvent, and unreacted acrylamide monomer in the polymer is substantially removed during the flocculation treatment. This is an aggregation treatment method.

The acrylamide-based polymer used in the present invention is an acrylamide homopolymer, a copolymer containing acrylamide as a main component, a modified product thereof by polymer reaction, or a mixture thereof.

As the comonomer, any compound can be used as long as it is copolymerizable with acrylamide. For example, the following comonomers can be used. methacrylamide,
(meth)acrylic acid, salts of (meth)acrylic acid, esters of (meth)acrylic acid, N of (meth)acrylamide
- Derivatives, (meth)acrylonitrile, (meth)acrolein, allylamine, pinyl acetate, vinyl chloride, vinylidene chloride, vinylpyridine, vinyl alkyl ether, styrene and its derivatives, vinylsulfonic acid and its derivatives, salts of these sulfonic acids, etc. . In addition to the above-mentioned compounds, for example, the following compounds can be used as comonomers.

As the ester of (meth)acrylic acid, monohydric or polyhydric alcohols such as monomethyl, ethyl, propyl,
Esters of butyl, hydroxyethyl or hydroxypropyl alcohol, esters of amino alcohols such as dimethylamino or dietylaminoethyl, dimethylamino or diethylaminopropanol or triethanolamine, N-transfers of (meth)acrylamide Examples include amides of (meth)acrylic acid and alkylene diamines, such as N-dimethylaminoethyl- or N-jethylaminopropyl-(meth)acrylamide, and also N-methylol-(meth)acrylamide or 2-(meth)acrylamide. -2-methylpropanesulfonic acid, vinyl alkyl ethers such as pinylmethyl ether or vinylethyl ether, styrene derivatives such as Q-methylstyrene or vinyltoluene, and vinylsulfonic acid derivatives such as vinylbenzenesulfone. acid or vinyltoluene-Q-sulfonic acid. The salts of (meth)acrylic acid and sulfonic acid compounds are preferably alkali metal salts, water-soluble alkaline earth metal salts or ammonium salts, especially sodium salts.

Comonomers having amino/groups, such as aminoalkyl esters of (meth)acrylic acid or N-dialkylaminoalkyl-(meth)acrylamides, can be prepared by reacting with acids, ammonium chloride, dimethyl sulfate, diethyl sulfate, methyl chloride, etc. It is also possible to use a quaternary ammonium compound derived from the above method, or it may be quaternized after copolymerization. The above-mentioned comonomers are appropriately selected depending on the properties of the resulting copolymer, such as water solubility, /ionicity, anionicity, or cationicity, and can be copolymerized with acrylamide alone or in a mixture of two or more. .

Homopolymerization and copolymerization of acrylamide can be carried out using any known method and conditions.

Anionic polymers. For example, they are produced by partially hydrolyzing polyacrylamide or by using (meth)acrylic acid, sulfonic acid compounds or salts of these acids as comonomers. The cationic polymer is
For example, it is produced by using a quaternary ammonium compound of an amino group-containing comonomer or by quaternizing the amino group in a polymer. A method for quaternizing polyacrylamide is described, for example, in Tsubaki Seki Sho 51-126293. The molecular weight of these polymers is generally 50
1,000,000 to 1,000, preferably 5,000,000 to 1,000, and 10,000,000 to 15,000,000 for nonions. The present inventors previously isolated several types of bacteria that have the ability to degrade and assimilate acrylamide monomers from soil, well water, etc., and among them, No. Bacterium No. 10021 was found to have particularly high activity. No. Bacterium No. 10021 belongs to the genus Nocardia and has been deposited as National Institute of Technology Bacteria Deposit No. 3451, and its taxonomic, physiological, and biochemical properties have been published in Tokubuta No. 51-2002 (Tokko No. 60-3). It is described in detail in the specification of Taruyusho No. 51-11507 (see Special Publication No. 53-76508).

No. 1 having the properties described in the above specification. In the present invention, Bacterium No. 10021, including its near green bacteria and mutant strains, will be referred to as "Bacteria of the genus Cardia having the ability to decompose acrylamide single bodies." That is, as long as it has the ability to decompose acrylamide monomer, No. In addition to Bacterium No. 10021, its near green bacteria and mutant strains can be used in the present invention. As with these bacteria, their enzymes are also used.

Extraction, separation, purification, etc. of the enzyme can be carried out by the method described in Tokuiso Sho 51-2002 Specification. In the present invention, crude enzyme may be used. In addition to the above-mentioned components, the flocculant of the present invention can contain conventional additives such as polymer thermal deterioration inhibitors, solubilizing agents, and the like.

As mentioned above, the high molecular weight acrylamide polymer produced by a known method may contain 0.1% by weight to several% by weight.
of unreacted acrylamide monomer.

Therefore, the amount of the Nocardia bacterium having an acrylamide-degrading facility as defined above or its enzyme used varies slightly depending on the amount of acrylamide monomer remaining in the polymer. No
．． In the case of Bacteria No. 10021, it is usually 0.001 to 5% by weight, preferably 0.0% by weight based on the acrylamide polymer.
It is added in an amount of 1-1% by weight. Enzymes have a more concentrated acrylamide monomer decomposition activity than bacteria, so the amount of enzyme used is generally 1/2 to 1/4 of the amount of bacteria.
That's enough. The flocculant of the present invention is prepared by adding the above-mentioned bacteria or enzymes to an acrylamide homopolymer, a modified product by a polymer reaction, a copolymer, or a mixture thereof as a dry product with a part of the substrate remaining if desired. By mixing using a powder mixing method, if the product is a liquid product, it can be manufactured by adding and mixing bacteria or enzymes as they are.

The flocculant mixture thus produced is preferably stored at room temperature or cold, and an enzyme stabilizer may also be added. The flocculant of the present invention can be used to flocculate and separate solid substances in water and aqueous solutions in the same manner as ordinary acrylamide flocculants, for example, for sedimentation of ores, treatment of various industrial wastewater, dewatering of sewage sludge, etc. can be used for agglomeration treatment. When used, the flocculant is dissolved in an aqueous solvent such as water or water containing salts, usually at a polymer concentration of 0.1 to 5% by weight. In the flocculant of the present invention in a dry state, the acrylamide decomposition activity of the bacterial cell enzymes described above is generally not exhibited, but when dissolved in water etc. during use, the acrylamide monomers present in the flocculant solution are It is effectively decomposed by the action of enzymes in a relatively short period of time, usually within several hours, at room temperature. Therefore, in a preferred embodiment of the flocculant of the present invention, the acrylamide polymer and the bacteria or their enzymes are stored separately, and then brought together at the time of use.

In this case, the acrylamide polymer and the bacteria or their enzymes can be mixed or separately added and dissolved in an aqueous solvent in any order, or the bacteria or their enzymes can be added to the polymer solution. For operational convenience, it is preferable to mix the two and then dissolve them. This method is particularly applicable when the product is in liquid form or when there is a risk of deterioration due to high temperature storage. In this way, the fear of deterioration due to high temperature storage etc. can be prevented. In addition, when using dried bacterial cells, the purpose can be achieved in a short time by aerating the cells during dissolution and processing. Unreacted acrylamide monomers contained in the polymer can be easily and substantially completely removed by using the Nocardia bacteria having the ability to decompose acrylamide monomers as defined above according to the present invention or its oxygen. .

Said bacteria or their oxygen can be used in all types of flocculants, nonionic, anionic and cationic, and have no adverse effect on their flocculating performance and hardly change the viscosity of the flocculant solution. This flocculant can be used in the same manner as conventionally known flocculants. Parts and percentages in the examples below relate to weight.

Quantification of acrylamide monomer was carried out by gas chromatography as follows. For the aqueous solution of the polymer and flocculant, a Perkin-Elmer gas chromatograph F-11 was used, Chromosolve was used as a carrier, the column (glass lm) temperature was 170°C, the injection temperature was 200°C, and the N2 gas was heated at 30°C/min. Under these conditions, a peak observed at an IJ tension time of approximately 6 minutes was measured from the quantitative curve using an FID detector. In addition, in order to investigate whether or not the addition and mixing of bacterial cells or enzymes has an effect on flocculation performance, we added and mixed bacterial cells or enzymes to determine the difference in performance between flocculant and those without additives using the commonly used flocculation measurement method. The viscosity was measured using a B-type viscometer in order to simply examine the difference in quality. Example 1 Anionic flocculant: Polyacrylamide partial hydrolyzate powder with a degree of hydrolysis of 15% (molecular weight 12 million, containing unreacted acrylamide monomer at pH 5000).

) 1 Oriko, No. Dried bacterial cells of bacteria No. 10021 0.0
Two parts were mixed to form a flocculant. This polyacrylamide partial hydrolyzate had a viscosity of 35 p as a 0.1% solution (using Yokohama city water). This flocculant was dissolved in tap water at room temperature to a concentration of 0.1%.

It was almost completely dissolved in about 2 hours, and the viscosity of the aqueous solution at this time was 32&p. The amount of acrylamide monomer in the aqueous solution immediately after dissolution was below the measurement limit and was substantially O-legged. Example 2 Nonionic flocculant: Polyacrylamide powder (degree of hydrolysis 0.5%, molecular weight approximately 12 million, containing 800 unreacted acrylamide monomers) 1 Ikari To'ko No. A flocculant was prepared by mixing 0.01 part of crude enzyme powder of Bacterium No. 10021.

This polyacrylamide had a viscosity of 280 p as a 1% solution (using Yokohama city water). This coagulant was dissolved in tap water at room temperature to a concentration of 1%.

It was almost completely dissolved in about 2 hours, and the viscosity of the aqueous solution at this time was 280 p. The amount of acrylamide monomer in the aqueous solution immediately after dissolution was substantially O-legged. In the same manner as above, 0.05 part of dried bacterial cells was used instead of oxygen and the mixture was dissolved under an aerated tube, and almost completely dissolved after 1.5 hours.

The viscosity did not change at 280 p. The amount of acrylamide monomer immediately after dissolution was O-legged. Example 3 Cationic flocculant: 10 parts of copolymer powder (containing 5000% unreacted acrylamide monomer) from 80% acrylamide and 20% dimethylaminoethyl methacrylate sulfate, N
o. 0.1 part of dried bacterial cells of Bacterium No. 10021 was mixed to prepare a flocculant.

This copolymer had a viscosity of 60 p as a 1% solution. This flocculant was dissolved in tap water at room temperature to a concentration of 1%.

It was almost completely dissolved in about 1 hour, and the viscosity of the aqueous solution at this time was 62&p. When the amount of acrylamide monomer in the aqueous solution was measured immediately after dissolution, almost no acrylamide monomer was detected. No significant difference was observed in the flocculation and dewatering performance of this flocculant for sewage sludge compared to that without bacterial cells.

Example 4 Cationic flocculant: Copolymer powder from 50% acrylamide and 50% trimethylaminoethyl methacrylate chloride (containing 3500 units of unreacted acrylamide monomer) 1 eave, no. 0.05 part of dried bacterial cells of Bacterium No. 10021 was mixed to prepare a flocculant.

This copolymer had a viscosity of 150 p as a 1% solution. This flocculant was dissolved in tap water at room temperature to a concentration of 0.5%.

After about 1 hour, it was almost completely melted, the viscosity of the aqueous solution at this time was 55 ratio p, and the amount of acrylamide monomer was O-leg.

No significant difference was observed in the flocculation and dewatering performance of this flocculant for sewage sludge compared to that without bacterial cells. Example 5 Copolymer 3 consisting of 50% acrylamide and 50% trimethylaminoethyl methacrylate methyl sulfate
100 parts of a 0% aqueous solution (viscosity approximately 500,000 cp) was dissolved in tap water of 300 ml. 0.3 part of crude enzyme powder of Bacterium No. 10021 was mixed.

A substantially uniform aqueous solution was obtained in about 30 minutes, and its viscosity was 5 ratio p. Immediately after melting, the amount of acrylamide monomer was mostly O-legged. Note that when only the copolymer was dissolved without adding crude enzyme, the concentration of acrylamide monomer was 50 capes. When the dewatering performance of both solutions for sewage sludge was compared, no significant difference was observed. Example 6 10% aqueous solution (viscosity 80,000 cp) of a polyacrylamide partial Mannich reaction product with a cation modification rate of 20%
part was dissolved in 10 times the volume of tap water, and at this time, No. 1002
0.1 part of dried bacterial cells of No. 1 bacteria was mixed.

Claims (1)

[Scope of Claims] 1. It is characterized by containing as an active ingredient an acrylamide homopolymer and/or a copolymer mainly composed of acrylamide, and a bacterium belonging to the genus Nocardia or an enzyme thereof having the ability to decompose acrylamide monomer. An acrylamide-based polymer flocculant capable of substantially removing unreacted acrylamide monomer in the polymer. 2. An acrylamide-based polymer flocculant containing an acrylamide homopolymer and/or a copolymer mainly composed of acrylamide, and a bacterium belonging to the genus Nocardia having the ability to decompose acrylamide monomers or its enzyme as an active ingredient, in an aqueous solvent. 1. A flocculation treatment method using an acrylamide-based polymer flocculant, characterized in that it is used in a flocculation treatment in the form of a dissolved acrylamide-based polymer flocculant, in which unreacted acrylamide monomer in the polymer zone is substantially removed. 3 Immediately before use, the acrylamide homopolymer and/or
or a copolymer containing acrylamide as a main component and a bacterium belonging to the genus Nocardia or an enzyme thereof having the ability to decompose an acrylamide monomer are dissolved in an aqueous solvent, according to claim 2. the method of.